U.S. patent application number 12/367091 was filed with the patent office on 2010-03-25 for apparatus and method for surface-treating carbon fiber by resistive heating.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Ha-jin KIM.
Application Number | 20100074834 12/367091 |
Document ID | / |
Family ID | 42037883 |
Filed Date | 2010-03-25 |
United States Patent
Application |
20100074834 |
Kind Code |
A1 |
KIM; Ha-jin |
March 25, 2010 |
APPARATUS AND METHOD FOR SURFACE-TREATING CARBON FIBER BY RESISTIVE
HEATING
Abstract
In an apparatus for surface-treating a carbon fiber, wherein the
carbon fiber is heated by resistive heating, a carbon-containing
gas is disposed on the carbon fiber, and carbon nanotubes are grown
on a surface of the carbon fiber.
Inventors: |
KIM; Ha-jin; (Yongin-si,
KR) |
Correspondence
Address: |
CANTOR COLBURN, LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
42037883 |
Appl. No.: |
12/367091 |
Filed: |
February 6, 2009 |
Current U.S.
Class: |
423/447.3 ;
204/157.47; 204/192.1; 204/199; 205/478; 205/548; 205/555;
977/749 |
Current CPC
Class: |
D01D 10/02 20130101;
D06M 10/06 20130101; C01B 32/162 20170801; D06M 11/74 20130101;
D06M 2101/40 20130101; B82Y 40/00 20130101; B82Y 30/00 20130101;
Y10T 428/30 20150115; D01F 9/127 20130101 |
Class at
Publication: |
423/447.3 ;
204/199; 205/555; 205/478; 205/548; 204/192.1; 204/157.47;
977/749 |
International
Class: |
D01F 9/127 20060101
D01F009/127 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2008 |
KR |
10-2008-0092923 |
Claims
1. An apparatus for surface-treating a carbon fiber, wherein the
carbon fiber is heated by resistive heating, a carbon-containing
gas is disposed on the carbon fiber, and carbon nanotubes are grown
on a surface of the carbon fiber.
2. The apparatus of claim 1, wherein the apparatus comprises: a
plurality of electrode rollers transferring the carbon fiber by a
rotational motion; and a power supply apparatus applying a voltage
between the plurality of electrode rollers, wherein the carbon
fiber moving between the plurality of electrode rollers is heated
by applying the voltage between the plurality of electrode
rollers.
3. The apparatus of claim 2, wherein the apparatus further
comprises a catalyst layer disposing apparatus configured to
dispose a catalyst layer, the catalyst layer comprising a catalyst
for growing carbon nanotubes on a surface of the carbon fiber.
4. An apparatus for surface-treating a carbon fiber, the apparatus
comprising: first and second electrode rollers transferring the
carbon fiber between the first and second electrode rollers by a
rotational motion and spaced apart from each other by an interval;
and a first power supply apparatus applying a voltage between the
first electrode roller and the second electrode roller, wherein the
carbon fiber moves between the first electrode roller and the
second electrode roller, the carbon fiber is heated by applying the
voltage between the first electrode roller and the second electrode
roller, a carbon-containing gas is disposed on the carbon fiber,
and carbon nanotubes are grown on a surface of the carbon fiber to
form a surface-treated carbon fiber.
5. The apparatus of claim 4, wherein the first and second electrode
rollers and the first power supply apparatus are placed in a
chamber having an oxygen-free atmosphere.
6. The apparatus of claim 5, wherein the carbon-containing gas is
disposed into the chamber and the carbon fiber is heated while
moving between the first electrode roller and the second electrode
roller.
7. The apparatus of claim 4, wherein at least one of a length and a
diameter of the carbon nanotubes depend on at least one factor
selected from the group consisting of a temperature of the carbon
fiber, a rotational speed of either of the first and second
electrode rollers, and the interval between the first and second
electrode rollers.
8. The apparatus of claim 4, wherein the carbon fiber is heated to
a temperature between about 300.degree. C. to about 1500.degree.
C.
9. The apparatus of claim 4, further comprising a bobbin on which
the surface-treated carbon fiber is wound.
10. The apparatus of claim 4, wherein a catalyst layer is disposed
on the surface of the carbon fiber, and the carbon nanotubes move
in a direction towards the first electrode roller, wherein the
catalyst layer comprises a catalyst for carbon nanotube growth, and
the carbon nanotubes have grown on the surface of the carbon
fiber.
11. The apparatus of claim 10, wherein the catalyst layer comprises
at least one element selected from the group consisting of Fe, Ni,
Co, Pd, Pt, Ir, and Ru.
12. The apparatus of claim 10, wherein the catalyst layer is
disposed by vacuum deposition, liquid deposition, or a combination
of vacuum deposition and liquid deposition.
13. The apparatus of claim 10, further comprising a catalyst layer
disposing apparatus configured to dispose the catalyst layer on the
surface of the carbon fiber.
14. The apparatus of claim 13, wherein the catalyst layer disposing
apparatus comprises: an electrolytic solution comprising a
catalytic metal; third and fourth electrode rollers moving the
carbon fiber by a rotational motion; and a second power supply
apparatus applying a voltage between the third and fourth electrode
rollers, wherein when the voltage is applied between the third and
fourth electrode rollers the catalyst layer is disposed on the
surface of the carbon fiber which moves in the electrolytic
solution.
15. The apparatus of claim 14, further comprising at least one
transfer roller transferring the carbon fiber on which the catalyst
layer is disposed by the catalyst layer disposing apparatus in a
direction towards the first electrode roller.
16. A method of surface-treating a carbon fiber, the method
comprising: heating the carbon fiber, wherein the heating comprises
resistive heating; disposing a carbon-containing gas on the carbon
fiber; and growing carbon nanotubes on a surface of the carbon
fiber.
17. The method of claim 16, wherein the heating further comprises
applying a voltage between a plurality of electrode rollers which
transfer the carbon fiber.
18. The method of claim 17, further comprising disposing a catalyst
layer comprising a catalyst for carbon nanotube growth on a surface
of the carbon fiber which is disposed between the plurality of
electrode rollers.
19. A method of surface-treating a carbon fiber, the method
comprising: transferring the carbon fiber from a first electrode
roller to a second electrode roller, wherein the first and second
electrode rollers are spaced apart from each other by an interval;
applying a voltage between the first and second electrode rollers;
heating the carbon fiber; disposing a carbon-containing gas on the
carbon fiber; and growing carbon nanotubes on a surface of the
carbon fiber to form a surface-treated carbon fiber.
20. The method of claim 19, wherein the first and second electrode
rollers and a first power supply apparatus are placed in a chamber
having an oxygen-free atmosphere, and the carbon-containing gas is
disposed into the chamber.
21. The method of claim 19, wherein at least one of a length and a
diameter of the carbon nanotubes depend on at least one factor
selected from a temperature of the carbon fiber, a rotational speed
of either of the first and second electrode rollers, and the
interval between the first and second electrode rollers.
22. The method of claim 19, wherein the carbon fiber is heated to a
temperature between about 300.degree. C. to about 1500.degree.
C.
23. The method of claim 19, wherein the method further comprises
packaging the surface-treated carbon fiber.
24. The method of claim 19, wherein the method further comprises
disposing a catalyst layer comprising a catalyst for carbon
nanotube growth on the surface of the carbon fiber.
25. The method of claim 24, wherein the catalyst layer comprises at
least one element selected from the group consisting of Fe, Ni, Co,
Pd, Pt, Ir, and Ru.
26. The method of claim 24, wherein the catalyst layer is disposed
by vacuum deposition, liquid deposition, or a combination of vacuum
deposition and liquid deposition.
27. The method of claim 26, wherein the vacuum deposition comprises
at least one of electron-beam evaporation, sputtering deposition,
and chemical vapor deposition, and the liquid deposition comprises
at least one of dip coating deposition, spray coating deposition,
electroless-plating deposition, and electro plating deposition.
28. The method of claim 24, wherein the disposing of the catalyst
layer comprises disposing the catalyst layer on the surface of the
carbon fiber in an electrolytic solution, the electrolytic solution
comprising a catalytic metal, wherein the disposing of the catalyst
layer includes applying a voltage between third and fourth
electrode rollers, the third and fourth electrode rollers
transferring the carbon fiber.
29. The method of claim 28, wherein the method further comprises
transferring the carbon fiber in a direction towards the first
electrode roller.
30. A surface-treated carbon fiber, comprising: carbon nanotubes
grown on a surface of a carbon fiber, wherein the carbon nanotubes
are grown by a method which comprises disposing a catalyst for
carbon nanotube growth on carbon fiber, heating the carbon fiber,
wherein the heating comprises resistive heating and applying a
voltage to a portion of the carbon fiber, disposing a
carbon-containing gas on the carbon fiber, and growing carbon
nanotubes on a surface of the carbon fiber.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority to Korean Patent
Application No. 10-2008-0092923, filed on Sep. 22, 2008, and all
the benefits accruing therefrom under 35 U.S.C. .sctn.119(a), the
contents of which in its entirety are herein incorporated by
reference.
BACKGROUND
[0002] 1. Field
[0003] This disclosure relates to an apparatus and method for
surface-treating carbon fiber by resistive heating.
[0004] 2. Description of the Related Art
[0005] A carbon fiber can have a carbon content of about 90 percent
("%"), or more. The carbon fiber can be produced from a precursor,
such as polyacrylonitrile ("PAN"), rayon, pitch, or the like which
is stabilized in an oxygen atmosphere, carbonized, and then
graphitized at a high temperature of about 1500.degree. C., or
more. Carbon fiber materials are high-function and high-strength
materials, and can have excellent specific modulus, specific
strength, thermal stability, corrosion resistance, conductivity,
vibration attenuation, and wear characteristics. Due to such
characteristics, carbon fiber materials can be used in various
applications, such as aerospace materials, reinforcing materials
for engineering or construction, sports or leisure products,
automobile parts or structures, pressure vessels, or external
materials for electronic devices. In most applications the carbon
fiber is not used alone but in a composite including a matrix. The
matrix can include a polymer, a ceramic, a metal, or the like. In
the composite, the carbon fiber can function as a reinforcing
material. The mechanical characteristics of the composite may
depend on characteristics of the matrix, characteristics of the
reinforcing material, the content of the reinforcing material, and
interfacial characteristics between the matrix and the reinforcing
material. It is desirable to improve interfacial adhesion between
the matrix and the reinforcing material. Improved interfacial
adhesion between a carbon fiber reinforcing material and a matrix
can contribute to improved strength and weight in a high-strength
lightweight composite.
[0006] An interfacial shear strength between a matrix and a
reinforcing material can be improved using chemical methods or
physical methods. In a chemical method, a chemical bonding force
between the matrix and the reinforcing material is increased. In a
physical method, an interfacial surface area between the matrix and
the reinforcing material is increased, thereby increasing a
physical bonding force between the matrix and the reinforcing
material. In addition, a physical bonding force between a matrix
and a reinforcing material including a carbon fiber can be
increased by treating the carbon fiber with microwaves or a plasma
to increase a surface roughness of the carbon fiber, or by
disposing a secondary phase on a surface of the carbon fiber.
However, when the surface roughness of the carbon fiber is
increased, using microwaves or a plasma, for example, one or more
of the characteristics of the carbon fiber can be degraded,
although the interfacial shear strength may be increased. On the
contrary, when a whiskerization process is performed on a surface
of a carbon fiber to increase a thickness and a surface area of an
interface between the carbon fiber and the matrix, the
characteristics of the carbon fiber may not be affected and the
interfacial shear strength can be increased by between about 200%
to about 300%. Accordingly, a method of increasing the thickness
and the surface area of the interface by whiskerization can be
effective for increasing a mechanical strength of a composite,
which can be achieved by improving the interfacial shear strength.
Accordingly, it is desirable to have a carbon fiber composite
having improved interfacial shear strength, as is an improved
method to provide whiskers on a carbon fiber surface.
SUMMARY
[0007] The above described and other drawbacks are alleviated by an
apparatus and a method for surface-treating a carbon fiber by
resistive heating.
[0008] Disclosed is an apparatus for surface-treating a carbon
fiber, wherein the carbon fiber is heated by resistive heating, a
carbon-containing gas is disposed on the carbon fiber, and carbon
nanotubes ("CNTs") are grown on a surface of the carbon fiber.
[0009] The apparatus may include: a plurality of electrode rollers
transferring the carbon fiber by a rotational motion; and a power
supply apparatus applying a voltage between the plurality of
electrode rollers, wherein the carbon fiber moving between the
plurality of electrode rollers is heated by applying the voltage
between the plurality of electrode rollers.
[0010] The apparatus may further include a catalyst layer disposing
apparatus configured to dispose a catalyst layer, the catalyst
layer including a catalyst for growing CNTs on a surface of the
carbon fiber.
[0011] Also disclosed is an apparatus for surface-treating a carbon
fiber, the apparatus including first and second electrode rollers
transferring the carbon fiber between the first and second
electrode rollers by a rotation motion and spaced apart from each
other by an interval; and a first power supply apparatus applying a
voltage between the first electrode roller and the second electrode
roller, wherein the carbon fiber moves between the first electrode
roller and the second electrode roller, the carbon fiber is heated
by applying the voltage between the first electrode roller and the
second electrode roller, a carbon-containing gas is disposed on the
carbon fiber, and CNTs are grown on a surface of the carbon fiber
to form a surface-treated carbon fiber.
[0012] The first and second electrode rollers and the first power
supply apparatus may be placed in a chamber having an oxygen-free
atmosphere.
[0013] In an embodiment the carbon-containing gas is disposed into
the chamber and the carbon fiber is heated while moving between the
first electrode roller and the second electrode roller.
[0014] In an embodiment, at least one of a length and a diameter of
the CNTs may depend on at least one factor selected from the group
consisting of a temperature of the carbon fiber, a rotational speed
of either of the first and second electrode rollers, and the
interval between the first and second electrode rollers.
[0015] The carbon fiber may be heated to a temperature between
about 300.degree. C. to about 1500.degree. C. In an embodiment, the
apparatus may further include a bobbin on which the surface-treated
carbon fiber is wound.
[0016] A catalyst layer which includes a catalyst for CNT growth
may be disposed on the surface of the carbon fiber, and the CNTs
move in a direction towards the first electrode roller, wherein the
catalyst layer comprises a catalyst for carbon nanotube growth, and
the CNTs may have grown on the surface of the carbon fiber.
[0017] The catalyst layer may include at least one element selected
from the group consisting of Fe, Ni, Co, Pd, Pt, Ir, and Ru. The
catalyst layer may be disposed by vacuum deposition, liquid
deposition, or a combination of vacuum deposition and liquid
deposition.
[0018] The apparatus may further include a catalyst layer disposing
apparatus configured to dispose the catalyst layer on the surface
of the carbon fiber. The catalyst layer disposing apparatus may
include: an electrolytic solution including a catalytic metal;
third and fourth electrode rollers moving the carbon fiber by a
rotational motion; and a second power supply apparatus applying a
voltage between the third and fourth electrode rollers, wherein
when the voltage is applied between the third and fourth electrode
rollers and the catalyst layer is disposed on the surface of the
carbon fiber which moves in the electrolytic solution.
[0019] The apparatus may further include at least one transfer
roller transferring the carbon fiber, on which the catalyst layer
is disposed by the catalyst layer disposing apparatus, in a
direction towards the first electrode roller.
[0020] Also disclosed is a method of surface-treating a carbon
fiber, the method including: heating the carbon fiber, wherein the
heating includes resistive heating; disposing a carbon-containing
gas on the carbon fiber; and growing CNTs on a surface of the
carbon fiber. In an embodiment, the heating further includes
applying a voltage between a plurality of electrode rollers which
transfer the carbon fiber. In an embodiment, the method further
includes disposing a catalyst layer including a catalyst for carbon
nanotube growth on a surface of the carbon fiber which is disposed
between the plurality of electrode rollers.
[0021] Also disclosed is a method of surface-treating a carbon
fiber, the method including: transferring the carbon fiber from a
first electrode roller to a second electrode roller, wherein the
first and second electrode rollers are spaced apart from each other
by an interval; applying a voltage between the first and second
electrode rollers; heating the carbon fiber; disposing a
carbon-containing gas on the heated carbon fiber; and growing CNTs
on a surface of the carbon fiber to form a surface-treated carbon
fiber.
[0022] The first and second electrode rollers and a first power
supply apparatus may be placed in a chamber having an oxygen-free
atmosphere, and the carbon-containing gas may be disposed into the
chamber.
[0023] In an embodiment, at least one of a length and a diameter of
the carbon nanotubes depend on at least one factor selected from a
temperature of the carbon fiber, a rotational speed of either of
the first and second electrode rollers, and the interval between
the first and second electrode rollers.
[0024] The carbon fiber may be heated to a temperature between
about 300.degree. C. to about 1500.degree. C. The method may
further include packaging the surface-treated carbon fiber.
[0025] The method may further include disposing a catalyst layer
including a catalyst for carbon nanotube growth on the surface of
the carbon fiber.
[0026] The catalyst layer may include at least one element selected
from the group consisting of Fe, Ni, Co, Pd, Pt, Ir, and Ru.
[0027] The catalyst layer may be disposed by vacuum deposition,
liquid deposition, or a combination of vacuum deposition and liquid
deposition.
[0028] The vacuum deposition may include at least one of
electron-beam evaporation, sputtering deposition, and chemical
vapor deposition, and the liquid deposition may include at least
one of dip coating deposition, spray coating deposition,
electroless-plating deposition, and electro plating deposition.
[0029] The disposing of the catalyst layer may include disposing
the catalyst layer on the surface of the carbon fiber in an
electrolytic solution, the electrolytic solution including a
catalytic metal, wherein the disposing of the catalyst layer may
include applying a voltage between third and fourth electrode
rollers, the third and fourth electrode rollers transferring the
carbon fiber.
[0030] The method may further include transferring the carbon fiber
in a direction towards the first electrode roller.
[0031] Also disclosed is a surface-treated carbon fiber, including:
carbon nanotubes grown on a surface of a carbon fiber, wherein the
carbon nanotubes are grown by a method including disposing a
catalyst for carbon nanotube growth on carbon fiber, heating the
carbon fiber, wherein the heating includes resistive heating, the
resistive heating including applying a voltage to a portion of the
carbon fiber, disposing a carbon-containing gas on the carbon
fiber, and growing carbon nanotubes on a surface of the carbon
fiber.
[0032] These and other features, aspects, and advantages of the
disclosed embodiments will become better understood with reference
to the following description and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The above and other aspects, advantages, and features of the
invention will become apparent and more readily appreciated from
the following further description of the embodiments, taken in
conjunction with the accompanying drawings in which:
[0034] FIG. 1 is a schematic illustration of an exemplary
embodiment of an apparatus for surface-treating a carbon fiber;
[0035] FIG. 2 is a schematic illustration of an exemplary
embodiment of an apparatus for surface-treating a carbon fiber
according to another embodiment; and
[0036] FIGS. 3 and 4 show electron microscopic images of exemplary
embodiments of carbon nanotubes, which are grown on an exemplary
embodiment of a surface of a carbon fiber.
DETAILED DESCRIPTION
[0037] Aspects, advantages, and features of the invention and
methods of accomplishing the same may be understood more readily by
reference to the following detailed description of disclosed
embodiments and the accompanying drawings. The invention may,
however, may be embodied in many different forms, and should not be
construed as being limited to the embodiments set forth herein.
Rather, these embodiments are provided so that this disclosure will
be thorough and complete and will fully convey the concept of the
invention to those skilled in the art, and the invention will only
be defined by the appended claims.
[0038] It will be understood that when an element or layer is
referred to as being "on" or "connected to" another element or
layer, the element or layer can be directly on or connected to
another element or layer or intervening elements or layers. In
contrast, when an element is referred to as being "directly on" or
"directly connected to" another element or layer, there are no
intervening elements or layers present. As used herein, the term
"and/or" includes any and all combinations of one or more of the
associated listed items.
[0039] It will be understood that, although the terms first,
second, third, etc., may be used herein to describe various
elements, components, regions, layers and/or sections, these
elements, components, regions, layers and/or sections should not be
limited by these terms. These terms are only used to distinguish
one element, component, region, layer, or section from another
region, layer, or section. Thus, a first element, component,
region, layer, or section discussed below could be termed a second
element, component, region, layer, or section without departing
from the teachings of the present invention.
[0040] Spatially relative terms, such as "below", "lower", "upper"
and the like, may be used herein for ease of description to
describe one element or feature's relationship to another
element(s) or feature(s) as illustrated in the figures. It will be
understood that the spatially relative terms are intended to
encompass different orientations of the device in use or operation
in addition to the orientation depicted in the figures. For
example, if the device in the figures is turned over, elements
described as "below" or "lower" relative to other elements or
features would then be oriented "above" relative to the other
elements or features. Thus, the exemplary term "below" can
encompass both an orientation of above and below. The device may be
otherwise oriented (rotated 90 degrees or at other orientations)
and the spatially relative descriptors used herein interpreted
accordingly.
[0041] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a," "an," and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0042] Embodiments of the invention are described herein with
reference to cross-section illustrations that are schematic
illustrations of idealized embodiments (and intermediate
structures) of the invention. As such, variations from the shapes
of the illustrations as a result, for example, of manufacturing
techniques and/or tolerances, are to be expected. Thus, embodiments
of the invention should not be construed as limited to the
particular shapes of regions illustrated herein but are to include
deviations in shapes that result, for example, from manufacturing.
Thus, the regions illustrated in the figures are schematic in
nature and their shapes are not intended to illustrate the actual
shape of a region of a device and are not intended to limit the
scope of the invention.
[0043] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0044] All methods described herein can be performed in a suitable
order unless otherwise indicated herein or otherwise clearly
contradicted by context. The use of any and all examples, or
exemplary language (e.g., "such as"), is intended merely to better
illustrate the invention and does not pose a limitation on the
scope of the invention unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed
element as essential to the practice of the invention as used
herein.
[0045] Hereinafter, the invention is described in detail with
reference to the accompanying drawings. However, the aspects,
features, and advantages of the invention are not restricted to the
ones set forth herein. The above and other aspects, features, and
advantages of the invention will become more apparent to one of
ordinary skill in the art to which the invention pertains by
referencing a detailed description of the invention given
below.
[0046] Carbon nanotubes ("CNTs") are lightweight and have excellent
thermal conductivity, electronic conductivity, and mechanical
strength characteristics. Due to such characteristics, CNTs are
regarded as a desirable reinforcing material for use in a composite
material. CNTs can be applied to a carbon fiber composite which
includes a carbon fiber and a matrix using at least two methods. In
a first method, functionalized CNTs are dispersed in the matrix so
that CNTs are disposed on a surface of the carbon fiber. In a
second method, CNTs are grown directly on a surface of the carbon
fiber. In the first method it can be desirable to functionalize and
disperse the CNTs. Thus the CNTs are dispersed in the matrix and
disposed on the surface of the carbon fiber, thereby reinforcing an
interface between the carbon fiber and the matrix. The first method
can result in a relatively small change in an interfacial shear
strength, as compared to the second method in which CNTs are grown
directly on the surface of the carbon fiber, and can be used in a
continuous process and in mass-production.
[0047] In the second method, in which CNTs are grown directly on a
surface of the carbon fiber, a catalyst for growing CNTs is
disposed on a surface of the carbon fiber and CNTs are formed using
chemical vapor deposition ("CVD") at a temperature between about
600.degree. C. to about 1100.degree. C., specifically about
700.degree. C. to 1000.degree. C., more specifically between about
800.degree. C. to about 900.degree. C. In the second method, CNTs
are disposed at an interface between the carbon fiber and the
matrix and thus a contact force at the interface is increased and,
due in part to the mechanical characteristics of CNTs, an
interfacial shear strength is increased. However, a method using
CVD can employ a high-temperature furnace which can have high power
consumption. Also, since CNTs can grow only in limited conditions,
a method using CVD can have high energy consumption and may not be
appropriate for a continuous process. Disclosed embodiments include
an apparatus and method for growing CNTs directly on a surface of a
carbon fiber by resistive heating.
[0048] Reference will now be made in detail to embodiments,
examples of which are illustrated in the accompanying drawings,
wherein like reference numerals refer to like elements throughout.
In the drawings, the thickness or size of respective elements is
exaggerated for clarity.
[0049] FIG. 1 is a schematic illustration of an exemplary
embodiment of an apparatus for surface-treating a carbon fiber.
[0050] Referring to FIG. 1, the apparatus for surface-treating a
carbon fiber includes a pair of first and second electrode rollers
120a and 120b, respectively, which are spaced apart from each other
at a selected interval and transfer a carbon fiber 110, and a power
supply apparatus 130 applying a voltage between the first and
second electrode rollers 120a and 120b. The carbon fiber 110 may be
derived from polyacrylonitrile ("PAN"), rayon, pitch, or the like,
or a combination comprising at least one of the foregoing
materials, and may have a content of carbon of about 80 percent
("%") or more, specifically about 90% or more, more specifically
about 95% or more. The specific resistance of the carbon fiber 110
may be between about 0.01 milliohms-centimeters ("m.OMEGA.cm") to
about 1000 m.OMEGA.cm, specifically between about 0.1 m.OMEGA.cm to
about 100 m.OMEGA.cm, more specifically between about 10 m.OMEGA.cm
to about 100 m.OMEGA.cm, but is not limited thereto.
[0051] The first and second electrode rollers 120a and 120b, and
the power supply apparatus 130, may be placed in a chamber 100. The
chamber 100 may have an oxygen-free atmosphere to reduce or
substantially prevent a reaction of carbon and oxygen inside the
chamber 100. In an embodiment, a power supply apparatus 130 may be
placed outside the chamber 100. The chamber 100 may further include
a first bobbin 140 supplying the carbon fiber 110 in a direction
towards the first electrode roller 120a. Herein, the carbon fiber
110 wound on the first bobbin 140 may be supplied in a direction
towards the first electrode roller 120a by a rotational motion of
the first bobbin 140.
[0052] In an embodiment, a catalyst layer (not shown), comprising a
catalyst for growing CNTs, may be disposed on the carbon fiber 110
which is supplied in a direction towards the first electrode roller
120a. The thickness of the catalyst layer may be between about 0.1
nanometer ("nm") to about 10 micrometers (".mu.m"), specifically
between about 0.2 nm to about 3 .mu.m, more specifically between
about 10 nm to about 1 .mu.m, but is not limited thereto. The
catalyst layer may be disposed by disposing a catalytic metal
having a selected thickness on a surface of the carbon fiber 110 by
vacuum deposition, liquid deposition, or the like, or a combination
comprising at least one of the foregoing methods. Vacuum deposition
may include electron-beam evaporation, sputtering deposition, CVD,
or the like, but is not limited thereto. Liquid deposition may
include dip coating deposition, spray coating deposition,
electroless-plating deposition, electro plating deposition, or the
like, but is not limited thereto. The catalytic metal may include
at least one transition metal selected from the group consisting of
Fe, Ni, Co, Pd, Pt, Ir, Ru, and the like. In an embodiment, the
catalytic metal may further include an ancillary catalytic metal to
improve catalytic characteristics of the transition metal. The
ancillary catalytic metal may include at least one of Mo, Cu, Al,
and the like.
[0053] The first and second electrode rollers 120a and 120b
transfer the carbon fiber 110 when rotating and can heat the carbon
fiber 110 which moves between the first and second electrode
rollers 120a and 120b in response to a voltage applied by the power
supply apparatus 130, up to a selected temperature. In this regard,
the temperature of the carbon fiber 110 may depend on the voltage
which is applied between the first and second electrode rollers
120a and 120b and an interval between the first and second
electrode rollers 120a and 120b. The carbon fiber 110 may be heated
to a temperature between about 200.degree. C. to about 1600.degree.
C., specifically between about 300.degree. C. to about 1500.degree.
C., more specifically between about 400.degree. C. to about
1400.degree. C., to grow CNTs.
[0054] In an embodiment, when the carbon fiber 110 which moves
between the first and second electrode rollers 120a and 120b is
heated, CNTs 112 grow on a surface of the carbon fiber 110. To grow
the CNTs 112, a carbon-containing gas is supplied into the chamber
100. The carbon-containing gas may include C.sub.2H.sub.2,
CH.sub.4, C.sub.2H.sub.6, CO, or the like, or a combination
comprising at least one of the foregoing carbon-containing gases.
The carbon-containing gas can also be a gas produced by thermally
decomposing alcohol, benzene, xylene, or the like, or a combination
comprising at least one of the foregoing materials. The
carbon-containing gas can also be selected from another carbon
supply source. In an embodiment, the carbon-containing gas may
further include Ar, H.sub.2, NH.sub.3, or the like, or a
combination comprising at least one of the foregoing gases.
[0055] The chamber 100 may further include a second bobbin 150 for
packaging a first surface-treated carbon fiber 111, which comprises
the CNTs 112. The first surface-treated carbon fiber 111 can pass
the second electrode roller 120b and can be wound on the second
bobbin 150, and is thereby packaged.
[0056] A process for growing the CNTs 112 on the carbon fiber 110
in the apparatus for surface-treating a carbon fiber described
above is hereinafter described in detail. First, the carbon fiber
110, on which the catalyst layer is disposed and which is wound on
the first bobbin 140, moves between the first electrode roller 120a
and the second electrode roller 120b. Then, the power supply
apparatus 130 applies a selected voltage between the first
electrode roller 120a and the second electrode roller 120b. As a
result, a current flows between the first electrode roller 120a and
the second electrode roller 120b, and the carbon fiber 110 is
heated due to the electrical resistance of the carbon fiber 110.
Accordingly, heat energy is generated on the surface of the carbon
fiber 110. The temperature of the carbon fiber 110 may depend on
the voltage applied between the first and second electrode rollers
120a and 120b, and the interval between the first and second
electrode rollers 120a and 120b.
[0057] When the carbon-containing gas is disposed on the heated
carbon fiber 110, on which the catalyst layer is disposed, the CNTs
112 grow on the surface of the carbon fiber 110 to form a first
surface-modified carbon fiber 111. The length and diameter of the
CNTs 112 may depend on, for example, the temperature of the carbon
fiber 110, the rotational speed of either or both of the first and
second electrode rollers 120a and 120b, and the interval between
the first and second electrode rollers 120a and 120b. In an
embodiment, when the first surface-modified carbon fiber 111, which
comprises the CNTs 112, passes by the second electrode roller 120b,
the growth of the CNTs 112 stops and the first surface-modified
carbon fiber 111 is wound on the second bobbin 150, and is thereby
packaged.
[0058] In an embodiment, the carbon fiber 110 may be locally heated
by resistive heating, and thus an energy efficiency of a process
for surface-treating a carbon fiber can be improved. In addition,
since the carbon fiber 110 can be supplied and the first
surface-treated carbon fiber packaged while the CNTs are being
grown, the disclosed method and the disclosed apparatus can be used
in a continuous, mass-production process. In an embodiment, the
chamber 100 can include only two electrode rollers for
resistive-heating carbon fiber, such as the first and second
electrode rollers 120a and 120b. In an embodiment the apparatus can
include greater than two electrode rollers.
[0059] FIG. 2 is a schematic illustration of an apparatus for
surface-treating a carbon fiber according to another
embodiment.
[0060] Referring to FIG. 2, the apparatus for surface-treating the
carbon fiber includes a catalyst layer disposing apparatus 300 for
disposing a catalyst layer on a surface of a carbon fiber 210' to
form a catalyst layer coated carbon fiber 210, and an apparatus for
receiving the catalyst layer coated carbon fiber 210, on which the
catalyst layer is disposed by the catalyst layer disposing
apparatus 300, and growing CNTs 212 on a surface of the catalyst
layer coated carbon fiber 210. The apparatus for growing the CNTs
212 may include a pair of first and second electrode rollers 220a
and 220b, respectively, and a first power supply apparatus 230 for
applying a voltage between the first and second electrode rollers
220a and 220b. The first and second electrode rollers 220a and
220b, and the first power supply apparatus 230, may be placed in a
chamber 200 having an oxygen-free atmosphere.
[0061] The first and second electrode rollers 220a and 220b
transfer the catalyst layer coated carbon fiber 210 supplied by the
catalyst layer disposing apparatus 300, and at the same time heat
the carbon fiber 210 which moves between the first electrode roller
220a and the second electrode roller 220b up to a selected
temperature using the voltage applied by the first power supply
apparatus 230. The temperature of the catalyst layer coated carbon
fiber 210 may depend on, for example, a voltage applied between the
first and second electrode rollers 220a and 220b, or an interval
between the first and second electrode rollers 220a and 220b. The
catalyst layer coated carbon fiber 210 may be heated to a
temperature between about 200.degree. C. to about 1600.degree. C.,
specifically between about 300.degree. C. to about 1500.degree. C.,
more specifically between about 400.degree. C. to about
1400.degree. C., to grow the CNTs 212. A carbon-containing gas may
be supplied into the chamber 200 to grow the CNTs 212. The chamber
200 may further include a second bobbin 250 for packaging a second
surface-treated carbon fiber 211, which includes the CNTs 212. The
second surface-treated carbon fiber 211 passes by the second
electrode roller 220b and can be wound on the second bobbin 250,
and thereby is packaged.
[0062] The catalyst layer disposing apparatus 300 disposes the
catalyst layer on a surface of the carbon fiber 210' by
electro-plating. The catalyst layer disposing apparatus 300
includes an electrolytic solution 360 which includes a selected
catalytic metal for growing CNTs, a pair of third and fourth
electrode rollers 320a and 320b, respectively, for moving the
carbon fiber 210' by a rotational motion, and a second power supply
apparatus 330 applying a voltage between the third and fourth
electrode rollers 320a and 320b. The catalytic metal included in
the electrolytic solution 360 may include at least one transition
metal selected from the group consisting of Fe, Ni, Co, Pd, Pt, Ir,
Ru, and the like. In an embodiment, the catalytic metal may further
include an ancillary catalytic metal to improve catalytic
characteristics of the transition metal. The ancillary catalytic
metal may include Mo, Cu, Al, or the like. The catalyst layer
disposing apparatus 300 may further include a first bobbin 340, for
supplying the carbon fiber 210' in a direction towards the third
electrode roller 320a. In the structure described above, when the
second power supply apparatus 330 applies a selected voltage
between the third and fourth electrode rollers 320a and 320b, the
catalyst layer (not shown) may be disposed on the surface of the
carbon fiber 210' which moves in the electrolytic solution 360. The
catalyst layer may be disposed to have a thickness between about
0.1 nanometer ("nm") to about 10 micrometers (".mu.m"),
specifically between about 0.2 nm to about 3 .mu.m, more
specifically between about 10 nm to about 1 .mu.m. The thickness of
the catalyst layer is not limited thereto. In FIG. 2, reference
numerals 351 and 352 denote first and second transfer rollers,
respectively, which transfer the carbon fiber 210' in the
electrolytic solution 360, and reference numerals 353, 354, and 355
denote third, fourth, and fifth transfer rollers, respectively,
which transfer the carbon fiber 210, on which the catalyst layer is
disposed by the catalyst layer disposing apparatus 300, in a
direction towards the first electrode roller 220a.
[0063] A method for growing the CNTs 212 on the carbon fiber 210'
in the apparatus for surface-treating a carbon fiber described
above is hereinafter described in detail. First, the carbon fiber
210' which is wound on the first bobbin 340 moves into the
electrolytic solution 360 by passing the third and fourth electrode
rollers 320a and 320b and the first and second transfer rollers 351
and 352, the latter of which can be placed in the electrolytic
solution 360. Then, when a voltage is applied between the third and
fourth electrode rollers 320a and 320b, the catalytic metal is
disposed on the surface of the carbon fiber 210' to form a catalyst
layer.
[0064] The carbon fiber 210, on which the catalyst layer is
disposed by the catalyst layer disposing apparatus 300, is guided
between the first and second electrode rollers 220a and 220b which
are placed in the chamber 200 by the third, fourth and fifth
transfer rollers 353, 354, and 355. The first power supply
apparatus 230 applies a selected voltage between the first
electrode roller 220a and the second electrode roller 220b. As a
result the catalyst layer coated carbon fiber 210 which moves
between the first electrode roller 220a and the second electrode
roller 220b is heated due to an electrical resistance of the
catalyst layer coated carbon fiber 210 until it reaches a selected
temperature. In this regard, the temperature of the catalyst layer
coated carbon fiber 210 may depend on the voltage applied between
the first and second electrode rollers 220a and 220b, and the
interval between the first electrode roller 220a and the second
electrode roller 220b. A carbon-containing gas is supplied into the
chamber 200 when the catalyst layer coated carbon fiber 210, which
comprises the catalyst layer, is heated and the CNTs 212 grow on
the surface of the catalyst layer coated carbon fiber 210. The
length and the diameter of the CNTs 212 may depend on a temperature
of the catalyst layer coated carbon fiber 210, a rotational speed
of either or both of the first and second electrode rollers 220a
and 220b, and an interval between the first electrode roller 220a
and the second electrode roller 220b. When the second
surface-treated carbon fiber 211, on which the CNTs 212 have grown,
passes by the second electrode roller 220b, the growth of the CNTs
212 stops and the second surface-treated carbon fiber 211 is wound
on the second bobbin 250 and is thereby packaged.
[0065] In an embodiment, a method of disposing a catalyst layer on
a surface of a carbon fiber by electroplating and a method of
growing CNTs on a surface of a carbon fiber, on which the catalyst
layer is disposed, can be performed at the same time. Thus the
disclosed method can be used in a continuous process, and the
disclosed continuous process can be desirable for mass-production.
In an embodiment, the catalyst layer is disposed on a surface of a
carbon fiber by liquid deposition and the liquid deposition can
comprise electro-plating. The disclosed embodiment is exemplary and
one of ordinary skill in the art would understand that it can be
modified in various forms by one of ordinary skill in the art. In
an embodiment, the catalyst layer disposing apparatus can be
configured as a dip coating apparatus, a spray coating apparatus,
an electroless-plating apparatus, or the like, or a combination
comprising at least one of the foregoing catalyst layer disposing
apparatuses.
[0066] FIGS. 3 and 4 show electron microscopic images of exemplary
embodiments of CNTs, which are grown on a surface of a carbon fiber
to form a surface-treated carbon fiber. Specifically, to form the
surface-treated carbon fiber shown in FIG. 3, a catalyst layer
comprising Invar, having a thickness of 1 nm and Al, having a
thickness of 2 nm, was disposed on the surface of the carbon fiber
by electron-beam evaporation Please consider further description of
the catalyst layer deposition, and then CNTs were grown on the
surface of the carbon fiber by a method comprising resistive
heating Please consider including a description of each exemplary
embodiment. To form the surface-treated carbon fiber shown in FIG.
4, a catalyst layer was disposed on a surface of a carbon fiber by
dip coating the carbon fiber in a solution comprising an iron
acetate liquid catalyst, and then CNTs were grown on the surface of
the carbon fiber by a method comprising resistive heating. The
surface-treated carbon fibers shown in FIGS. 3 and 4, respectively,
were derived from a K63712 pitch-based carbon fiber produced by
Mitsubishi Chemical Co. The interval between two electrode rollers
during resistive heating was 4 cm, and the voltage applied between
the two electrode rollers and the current flowing between the two
electrode rollers were respectively 8.8 volts ("V") and 340
milliamperes ("mA"). In addition, C.sub.2H.sub.2gas and Ar gas were
supplied into a chamber to grow the CNTs, and the time period for
growing the CNTs was 10 minutes.
[0067] In an embodiment, CNTs are grown on a surface of a carbon
fiber and a physical binding force between the carbon fiber and a
matrix, and a surface area of an interface between the carbon fiber
and the matrix, are increased. Thus an interfacial shear strength
can be improved. Accordingly, stresses generated by a force
disposed on a composite material can be distributed, and thus
mechanical characteristics of the composite material can be
improved. In addition, since the carbon fiber can be locally heated
by resistive heating in a method to grow CNTs, energy consumption
is reduced and heating and cooling time periods can be reduced, and
thus a yield of a manufacturing process to produce the
surface-treated carbon fiber can be improved. The reduced energy
consumption and improved yield can desirably reduce a cost of the
surface-treated carbon fiber. In addition, since in an embodiment
the carbon fiber is continuously supplied, and the surface-treated
carbon fiber is continuously packaged during the disclosed CNT
growth process, in an embodiment mass-production can be a
continuous process.
[0068] While this disclosure describes exemplary embodiments, it
will be understood by those skilled in the art that various changes
can be made and equivalents can be substituted for elements thereof
without departing from the scope of the disclosed embodiments. In
addition, many modifications can be made to adapt a particular
situation or material to the teachings of this disclosure without
departing from the essential scope thereof. Thus the exemplary
embodiments described herein should be considered in a descriptive
sense only and not for purposes of limitation. Descriptions of
features or aspects within each embodiment should be considered as
available for other similar features or aspects in other
embodiments, where appropriate. Therefore, it is intended that this
disclosure not be limited to the particular embodiment disclosed as
the best mode contemplated for carrying out this disclosure.
* * * * *